The present invention relates to a seat belt anchorage plate for a seat belt device for attaching the end of, for example, a seat belt for an automobile to a fixed part such as a vehicle body.
Conventionally, as such kind of seat belt anchorage plate, a plate illustrated in FIG. 38 has been well known. That is, a seat belt anchorage plate comprises a base (plate shaped member) 2 having a bolt hole 3 and a slot 69 formed thereon and is designed to be secured to a fixed part such as a vehicle body through the bolt hole 3 and to be connected to a belt 13 through the slot 69.
The belt 13 employs a thin band shaped woven fabric in which for example, polyester fibers are woven and is folded back in one long edge part 691-8 of the slot 69, so that tension is exerted on the one long edge part 691-8 which is linearly formed.
Since the above mentioned conventional seat belt anchorage plate has one long edge part 691-8 formed in a straight line, when the tension of the belt 13 is not exerted in the direction perpendicular to the one long edge part 691-8, the belt 13 is liable to laterally slide on the one long edge part 691-8 and come together to the end part of the long edge part 691-8. In other words, there has been encountered a problem that the belt is apt to be gathered to the end part of one long edge part 691-8. Even if the tension of the belt 13 is exerted in the direction perpendicular to the one long edge part 691-8, for example, according to an examination through a strength measuring test, the belt 13 itself will be thinly converged and tend to meet at one part on the one long edge part 691-8 when the tension is exerted on the belt 13. Further, since the one long edge part 691-8 is elastically bent and slightly recessed by virtue of the tension of the belt 13, the belt 13 is undesirably liable to be gathered to one part on the long edge part 691-8 in addition to the defect that the belt 13 itself thinly converges into one part.
Further, the belt 13 is advantageously curved so as to be folded along a center line in its longitudinal direction in order to maintain the flat state of the belt 13. Therefore, the belt 13 is normally inserted into the slot 69 under its curved state as stated above. However, when the belt 13 is curved in such a way, there arises a problem that both ends at the right and left sides of the belt 13 abut against, for example, both right and left ends of the one long edge part 691-8, and therefore, the belt 13 is inserted into the slot 69 with difficulty. As shown in FIG. 38, when both the end parts of the belt 13 swell out roundly, there also arises a problem that these swelling parts tend to more easily abut against both the end parts of one long edge part 691-8.
Still further, the slot 69 is formed by a press working. In this case, burs are liable to be formed at the corner parts in the side punched out by a press. When such burs are left as they are, they have possibility to cause an action similar to that of a cutter. Accordingly, the corner parts are ordinarily subjected to a rounding finish independent of a press working process, or a coating works to cover the entire corner parts with vinyl chloride or polyethylene or the like. As a result, there has been encountered a problem in terms of cost-up owing to such a finishing work or a coating work.
Additionally stated, as illustrated in FIG. 39, since a seat belt anchorage plate is formed with a plate shaped base 2, the area of one long edge part 691-8 for holding the belt 13 is small, so that surface pressure exerting on the belt 13 is disadvantageously increased.
The present invention was made by taking these problems into account and an object of the present invention is to provide a seat belt anchorage plate for a seat belt device and a method for manufacturing it capable of completely reducing surface pressure to be exerted on the belt even when tension acts on the belt.
In order to achieve the above described object, a feature of the invention is a seat belt anchorage plate for a seat belt device which is formed with a plate shaped member, the plate shaped member having a slot formed into which the belt is inserted; the slot having long edge parts opposed to each other one of which bears the tension of the belt folded back therein; and one of the long edge parts being formed to expand toward a central part from both end parts in its longitudinal direction.
The Invention also concerns a seat belt anchorage plate for a seat belt device formed with a plate shaped member having a slot into which the belt is inserted and which has long edge parts opposed to each other, the belt being folded back in one of the long edge parts so that the one long edge part bears the tension of the belt, wherein the one long edge part is formed so as to swell in the direction opposite to that of the tension of the belt toward a central part from both end parts in its longitudinal direction.
Another feature of the invention concerns the other long edge part opposed to the one long edge part being formed so as to extend along the one long edge part.
The invention also concerns the one long edge part being formed so that it is provided with a protrusion protruding from one surface of the plate shaped member and its cornerparts are rounded along the direction in which the belt is folded back.
The invention concerns the one long edge part being formed so as to have a protrusion which protrudes from the other side of the plate shaped member by bending a part of the plate shaped member from one surface side to the other surface side so that an area against which the belt abuts is increased and corner parts are rounded along the direction in which the belt is folded back due to the existence of the protrusion.
Another feature of the invention is the long edge part being formed so as to have one protrusion and the other protrusion respectively protruding from one surface and the other surface of the plate shaped member and their corner parts are rounded.
The invention also concerns the one long edge part being formed so as to have one protrusion and the other protrusion respectively protruding from one surface side and the other surface side of the plate shaped member by bending a part of the plate shaped member from one surface side to the other surface side of the plate shaped member and pressing the bent part to return to the one surface side, so that an area against which the belt abuts is increased owing to the one protrusion and the other protrusion, and further, their corner parts are rounded along the direction on which the belt is folded back.
The invention includes short edge parts except the one long edge part in the slot for connecting at least one long edge part to the other long edge part are formed so as to have a protrusion similar to that of the one long edge part.
The invention includes short curved edges for connecting the one long edge part to the other long edge part.
The invention includes a seat belt anchorage plate for a seat belt device formed with a plate shaped member, the plate shaped member having a slot formed thereon into which the belt is inserted; the slot having long edge parts opposed to each other, the belt being folded back in one of the long edge parts which bears the tension of the belt; and the one long edge part having a protrusion which protrudes from at least one surface of the one surface and the other surface of the plate shaped member.
The includes short edge parts except the one long edge part in the slot for connecting at least one long edge part to the other long edge part are formed so as to have a protrusion similar to that of the one long edge part.
Another feature of the invention includes the one long edge part having corner parts rounded along the direction in which the belt is folded back.
The invention includes respective protrusions having the amount of protrusion from the plate shaped member ranging from 15% to 60% as thick as the thickness of the plate shaped member.
The invention also concerns a method for manufacturing a seat belt anchorage plate for a seat belt device formed with a plate shaped member which has a slot formed into which the belt is inserted, the slot having an edge part provided with a protrusion which protrudes from the one surface of one surface and the other surface of the plate shaped member, the method comprising: a piercing step for punching out the preliminary hole of the slot from the plate shaped member; a burring step for forming a slot by pushing a punch larger than this preliminary hole thereinto and pushing out a part of the plate shaped member along this slot to form a protrusion; and a curved surface forming step for surface-pressing the protrusion formed in the burring step and rounding corner parts.
Additionally, the invention concerns a method for manufacturing a seat belt anchorage plate for a seat belt device formed with a plate shaped member which has a slot formed into which a belt is inserted, the slot having an edge part provided with a protrusion which protrudes from the one surface of the one surface and the other surface of the plate shaped member; the method comprising: a piercing step for punching out the preliminary hole of the slot from the plate shaped member; a surface-pressing step for removing sheared edge parts (burs) produced in the piercing step; a burring step for forming a slot by pushing a punch larger than this preliminary hole thereinto and forming a protrusion by pushing out a part of the plate shaped member along this slot; a curved surface forming step for surface-pressing the protrusion formed in the burring step and rounding corner parts; a restriking step for smoothly rounding edge parts opposite to the protrusion in the slot; and a separating step for cutting a seat belt anchorage plate with a prescribed form.
When tension is exerted upon the belt, the part of the belt which is reflected in one long edge part is tightly fixed to that one long edge part. Namely, the part of the belt which is folded back takes a configuration in which its central part in its lateral direction expands similarly to the one long edge part. As a result, the belt hardly slides laterally along the one long edge part. Therefore, even if the direction of the tension of the belt does not coincide with the direction perpendicular to the one long edge part, the belt will not slide sideward along the one long edge part so that it does not gather to the end part of the belt.
Further, since the central part of the belt in its lateral direction swells similarly to that of the one long edge part, the belt is always brought into a state in which it is expanded in its lateral direction. Accordingly, even when the belt itself tends to thinly converge upon exertion of tension on the belt, the width of the belt is maintained in an original state in the one of the long edges. That is, the belt does not gather at one part on the one long edge part. In addition, since the one long edge part expands in the direction opposite to the tension, even when the one long edge part is slightly elastically deformed toward the direction of tension, this one long edge part is not recessed depending on the tension of the belt. Thus, the belt does not come together to the recessed part of the one long edge part, either. As mentioned above, since the width of the belt is properly maintained in the one long edge part, the tension of the belt is evenly transmitted to the one long edge part. Consequently, the durability of the belt and the seat belt anchorage plate can be improved and safety can be improved owing to the improvement of their durability.
Further, where the belt is formed by pressing and flattening a tubular member in a flat shape, the belt is preferably curved so as to be folded along the central line in its longitudinal direction in order to maintain the flattened shape of the belt. Also when the belt is inserted into the slot while it is curved in such a manner, both the end parts at the right and left sides of the belt hardly strike against both the end parts of the one long edge parts, since the central part of the one long edge part is so formed as to swell and the curved shape of the belt substantially coincides with the shape of one long edge part. Additionally, rounded and expanded parts at both the ends of the also hardly strike against the one long edge part. Therefore, the belt can be easily inserted into the slot.
Since the other long edge part opposed to one long edge part is so formed as to extend along the one long edge part, the configuration of the one or the other, long edge part substantially correspond to that of the belt curved as stated above. Thus, the belt can be more easily inserted into the slot than in the case mentioned above.
Particularly, since short edge parts through which the one long edge part is connected to the other long edge part are formed in curved shapes of circular arc which are smoothly continued from one and the other long edge parts, the rounded and expanded parts at both the ends of the belt hardly collide with the short edge parts. Thus, the belt can be advantageously more readily inserted into the slot.
Since the one long edge part has a protrusion which protrudes from one surface side of the plate shaped member, the contact surface area of the belt abutting against the one long edge part is increased. As a result, the surface pressure of the belt can be reduced. Further, since the corner parts of the one long edge part are rounded along the direction in which the belt is folded back, the belt is prevented from breaking in the corner parts. Furthermore, since the corner parts are rounded and these corner parts do not need to undergo a coating work with vinyl chloride or polyethylene or the like, cost required for such a coating work can be reduced. That is, the cost can be lowered.
Since a protrusion which protrudes from the other surface of the plate shaped member is formed by bending a part of the plate shaped member from the one surface side to the other surface side of the plate shaped member, the protrusion can be projected greatly from the other surface side. Therefore, the area of the belt abutting against the one long edge part can be increased. In other words, surface pressure exerted on the belt from the one long edge part can be completely lowered. Therefore, the durability of the belt and the strength of the seat belt anchorage plate can be improved, and safety can be improved based on the improvement of their durability and strength. Further, since the corner parts of the one long edge part are rounded, the belt can be prevented from being broken in these corner parts. Additionally, since the corner parts are rounded and do not need to be subjected to a coating work with vinyl chloride or polyethylene or the like, cost necessary for such a coating work can be reduced. Namely, the cost can be lowered.
Since the one long edge part is formed so as to have one protrusion and the other protrusion which respectively protrude from one surface side and the other surface side of the plate shaped member, the contact surface area of the belt which abuts against the one long edge part is increased in some embodiments of the invention. As a result, the surface pressure of the belt can be further reduced.
Since the one long edge part is formed so as to have one protrusion and the other protrusion which respectively protrude from one surface side and the other surface side by bending a part of the plate shaped member from the one surface side to the other surface side of the plate shaped member and pressing the bent part to return to the one surface side, the area of a part against which the belt abuts can be increased in some embodiments of the invention. Consequently, the surface pressure of the folded-back part of the belt can be further reduced.
The short edge parts are also provided with a protrusion, so that the strength of the short edge parts can be increased. Therefore, even if the belt is gathered to the short edge part so that force is concentrated to the short edge part, the safety of the short edge part can be more improved than the past until the present. In addition, where a whole edge part except the one long edge part is also provided with a protrusion, the strength of an entire part around the slot can be improved.
Since the operational advantages as mentioned above can be exhibited, and the short edges are formed to be curved in a circular arc shape, the concentration of stress to the short edge parts can be relieved.
The contact surface area the belt which abuts against the one long edge part can be increased owing to the presence of the protrusion. As a result, the surface pressure of the belt can be reduced. Where the protrusions are formed so as to protrude from both the one surface side and the other surface side of the plate member, the surface pressure of the belt can be most reduced.
Since the corner parts of the one long edge part are rounded along the direction in which the belt is folded back, the belt can be prevented from being broken in these corner parts. Further, since the corner parts are rounded and they do not need to undergo a coating work with vinyl chloride or polyethylene or the like, expenses required for such a coating work can be reduced. That is, the cost can be lowered.
The amount of protrusion of the respective protrusions which are projected from the plate shaped member ranges from 15% to 60% as thick as the thickness of the plate shaped member, so that the contact surface area of the belt which abuts against the one long edge part can be increased. Such a magnification as 15% to 60% is enabled by forming the part of the slot by a bending work in some embodiments of the invention, or forming it by burring in other embodiments of the invention.
Since the sheared edge parts (burs) produced in a piercing step are removed in a surface pressing step, the protrusion can be clearly projected in a burring step and the corner parts of the protrusion can be finely formed in a curved surface forming step.
The edge part opposite to the protrusion in the slot can be smoothly rounded with a larger radius of curvature in a restriking step. Therefore, since the corner parts can be finished so as to be rounded in a series of press working steps for forming the seat belt anchorage plate, a finishing work or a coating work must not be carried out in another step. Accordingly, the cost can be reduced.